Clear FEC buffer on new dred packet

Fixes "FEC buffer full" issue

lpcnet @ 0ac0d1df

-Subproject commit dc30fbef3fe48fa9e5d87860c6b21efb02db5f45
+Subproject commit 0ac0d1df9a586db99b7ee00b69b3542d701c220e

src/opus_decoder.c

@@ -1118,10 +1118,13 @@ int opus_decoder_dred_input(OpusDecoder *st, const unsigned char *data,
    if (payload != NULL)
    {
       int min_feature_frames;
+      silk_decoder_state *silk_dec;
+      silk_dec = (silk_decoder_state*)((char*)st+st->silk_dec_offset);
       /*printf("Found: %p of size %d\n", payload, payload_len);*/
       min_feature_frames = IMIN(2 + offset, 2*DRED_NUM_REDUNDANCY_FRAMES);
       st->nb_fec_frames = dred_decode_redundancy_package(&st->dred_decoder, st->fec_features, payload, payload_len, min_feature_frames);
-      return 1;
+      lpcnet_plc_fec_clear(silk_dec->sPLC.lpcnet);
+      return st->nb_fec_frames;
    }
    return 0;
 }